/*
* Copyright 2002-2019 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.core;
import java.util.function.Function;
import org.reactivestreams.Publisher;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
Adapter for a Reactive Streams Publisher
to and from an async/reactive type such as CompletableFuture
, RxJava Observable
, and others. An adapter is typically obtained via ReactiveAdapterRegistry
.
Author: Rossen Stoyanchev Since: 5.0
/**
* Adapter for a Reactive Streams {@link Publisher} to and from an async/reactive
* type such as {@code CompletableFuture}, RxJava {@code Observable}, and others.
*
* <p>An adapter is typically obtained via {@link ReactiveAdapterRegistry}.
*
* @author Rossen Stoyanchev
* @since 5.0
*/
public class ReactiveAdapter {
private final ReactiveTypeDescriptor descriptor;
private final Function<Object, Publisher<?>> toPublisherFunction;
private final Function<Publisher<?>, Object> fromPublisherFunction;
Constructor for an adapter with functions to convert the target reactive
or async type to and from a Reactive Streams Publisher.
Params: - descriptor – the reactive type descriptor
- toPublisherFunction – adapter to a Publisher
- fromPublisherFunction – adapter from a Publisher
/**
* Constructor for an adapter with functions to convert the target reactive
* or async type to and from a Reactive Streams Publisher.
* @param descriptor the reactive type descriptor
* @param toPublisherFunction adapter to a Publisher
* @param fromPublisherFunction adapter from a Publisher
*/
public ReactiveAdapter(ReactiveTypeDescriptor descriptor,
Function<Object, Publisher<?>> toPublisherFunction,
Function<Publisher<?>, Object> fromPublisherFunction) {
Assert.notNull(descriptor, "'descriptor' is required");
Assert.notNull(toPublisherFunction, "'toPublisherFunction' is required");
Assert.notNull(fromPublisherFunction, "'fromPublisherFunction' is required");
this.descriptor = descriptor;
this.toPublisherFunction = toPublisherFunction;
this.fromPublisherFunction = fromPublisherFunction;
}
Return the descriptor of the reactive type for the adapter.
/**
* Return the descriptor of the reactive type for the adapter.
*/
public ReactiveTypeDescriptor getDescriptor() {
return this.descriptor;
}
Shortcut for getDescriptor().getReactiveType()
. /**
* Shortcut for {@code getDescriptor().getReactiveType()}.
*/
public Class<?> getReactiveType() {
return getDescriptor().getReactiveType();
}
Shortcut for getDescriptor().isMultiValue()
. /**
* Shortcut for {@code getDescriptor().isMultiValue()}.
*/
public boolean isMultiValue() {
return getDescriptor().isMultiValue();
}
Shortcut for getDescriptor().isNoValue()
. /**
* Shortcut for {@code getDescriptor().isNoValue()}.
*/
public boolean isNoValue() {
return getDescriptor().isNoValue();
}
Shortcut for getDescriptor().supportsEmpty()
. /**
* Shortcut for {@code getDescriptor().supportsEmpty()}.
*/
public boolean supportsEmpty() {
return getDescriptor().supportsEmpty();
}
Adapt the given instance to a Reactive Streams Publisher
. Params: - source – the source object to adapt from; if the given object is
null
, ReactiveTypeDescriptor.getEmptyValue()
is used.
Returns: the Publisher representing the adaptation
/**
* Adapt the given instance to a Reactive Streams {@code Publisher}.
* @param source the source object to adapt from; if the given object is
* {@code null}, {@link ReactiveTypeDescriptor#getEmptyValue()} is used.
* @return the Publisher representing the adaptation
*/
@SuppressWarnings("unchecked")
public <T> Publisher<T> toPublisher(@Nullable Object source) {
if (source == null) {
source = getDescriptor().getEmptyValue();
}
return (Publisher<T>) this.toPublisherFunction.apply(source);
}
Adapt from the given Reactive Streams Publisher.
Params: - publisher – the publisher to adapt from
Returns: the reactive type instance representing the adapted publisher
/**
* Adapt from the given Reactive Streams Publisher.
* @param publisher the publisher to adapt from
* @return the reactive type instance representing the adapted publisher
*/
public Object fromPublisher(Publisher<?> publisher) {
return this.fromPublisherFunction.apply(publisher);
}
}